i think you're thinkin of the air screw. this adjusts the amount of air fed into the pilot circuit and needs to be tuned the pilot jet. this will be affected mainly by altitude, temp and barometric pressure.
the idle control is a large thumbscrew w/ a slot in it. it lives between the tank and the seat. remove the seat and you'll see it right under the tank.
unless of course your carb is not the stocker or you did the full tors removal w/ a new carb cap.